Nuclear disarmament: Bombs away

On his return home, Dmitry Medvedev hailed Barack Obama as "my new comrade". The Russian president said he was not seeking the end of Nato by proposing a new security pact for Europe, and his Nato ambassador, Dmitry Rogozin, a hardwired nationalist, said he would not rule out joining the transatlantic alliance one day. And this from the land which greeted Mr Obama's election with the announcement that it would deploy short-range missiles in Kaliningrad if America installed a missile defence battery over the border in Poland. What a difference a 70-minute meeting in London makes. Meanwhile, comrade Obama will outline in Prague tomorrow an agenda for a world without nuclear weapons. Yesterday world prosperity. Today world peace. Not a bad week's work.

Nothing of substance has changed - the core differences between Nato and Russia remain. But the tone of the dialogue has changed and that does matter. Instead of winding each other up, the two most important nuclear powers are finding ways to talk about each other in less belligerent ways. Getting to zero, or getting to the point of eliminating nuclear weapons, has been around as an idea almost as long as the weapons themselves have been. It has bipartisan support in America, with backers including George Shultz, Henry Kissinger, William Perry and Sam Nunn. Recently, however, the zero option has received fresh impetus. One of Mr Obama's first acts was to end development work on a "reliable replacement warhead" which critics said was a cover for designing new weapons. Reaffirming Britain's decision to replace Trident, Gordon Brown said Britain would reduce the number of missile tubes on each submarine from 16 to 12. Nothing new there, but he added an intriguing rider. He said that if it was possible to reduce the number of UK warheads further, "consistent with the progress of multilateral discussions", Britain would be ready to do so. These are straws in the wind.

It is not known what progress Mr Obama and Mr Medvedev made on the numbers of warheads that would be negotiated in a replacement for the Start treaty, which expires at the end of the year. Under a different treaty which governs warheads that are "operationally deployed", Russia has an arsenal of 2,700 warheads which would be reduced to between 1,700 and 2,200 by 2012. The US has already met that requirement, but both countries are still thought to hold thousands of additional warheads which are not deployed. The scope for deep cuts in the nuclear arsenal is huge.

Other measures could lower the temperature further. One legacy of the cold war is the forward deployment of between 200 and 350 US nuclear bombs in Germany, Italy, the Netherlands, Belgium and Turkey. Nato's nuclear umbrella was designed as a deterrent against Soviet conventional invasion. But the boot is now on the other foot. Russia's conventional forces have been so weakened in relation to Nato's that they will be more resistant to the zero option than the US will be. Getting rid of an obsolete stockpile of freefall bombs in Nato countries would be an important first step. It would also put Nato in a stronger position to demand stronger non-proliferation mechanisms.

Nato has other problems, like how to defeat a resurgent Taliban in Afghanistan. The question of burden-sharing between Europe and America will be of greater and more immediate consequence in Afghanistan - now that American troops will be double the size of the force from other Nato members - than it will be on the issue of nuclear stockpiles. Nato could use Russia's help in the transit of non-lethal military supplies, as convoys through Pakistan are coming under attack. But the bigger picture of nuclear disarmament and non-proliferation does affect the smaller one. Together it creates a world where security is shared. This is a vision worth fighting for.